Surface treating appliances such as vacuum cleaners and floor polishers are well known. The majority of vacuum cleaners are either of the ‘upright’ type or of the ‘cylinder’ type, called canister or barrel cleaners in some countries. An example of an upright vacuum cleaner manufactured by Dyson Limited under the name DC04 (“DC04” is a trade mark of Dyson Limited) is shown in FIG. 1. The vacuum cleaner comprises a main body 102 which houses the main components of the vacuum cleaner. A lower part 106 of the main body houses a motor and fan for drawing dirty air into the machine and the main body also houses some form of separating apparatus 104 for separating dirt, dust and other debris from a dirty airflow drawn in by the fan. The main body 102 also houses filters for trapping fine particles in the cleaned airflow. A cleaner head 108 is rotatably mounted, about points A, to the lower end of the main body 102. The axis about which the cleaner head rotates is horizontally directed. A supporting wheel 107 is mounted on each side of the lower part 106 of the main body, in a fixed relationship to the main body 102. In use, a user reclines the main body 102 of the vacuum cleaner and then pushes and pulls a handle 116 which is fixed to the main body of the cleaner. The vacuum cleaner rolls along the floor surface on the supporting wheels 107.
A dirty-air inlet 112 is located on the underside of the cleaner head 108. Dirty air is drawn into the dust separating apparatus 104 via the dirty-air inlet 112 by means of the motor-driven fan. It is conducted to the dust separating apparatus 104 by a first air flow duct. When the dirt and dust entrained within the air has been separated from the airflow in the separating apparatus 104, air is conducted to the clean air outlet by a second air flow duct, and via one or more filters, and expelled into the atmosphere.
Conventional upright vacuum cleaners have a disadvantage in that they can be difficult to manoeuvre about an area in which they are used. They can be pushed and pulled easily enough, but pointing the cleaner in a new direction is more difficult. The cleaner can be pointed in a new direction by applying a sideways directed force to the handle, either from standstill or while moving the cleaner forwards or backwards. This causes the cleaner head to be dragged across the floor surface so that it points in a new direction. The only articulation between the main body 102 and the cleaner head 108 is about horizontally directed axis A, which remains parallel with the floor surface. In some upright vacuum cleaners the supporting wheels 107 are mounted on the cleaner head rather than the main body. However, the main body is rotatably mounted to the cleaner head about a horizontally directed axis, as just described.
Attempts have been made to increase the maneuverability of upright vacuum cleaners. Some examples of upright vacuum cleaners with improved maneuverability are shown in U.S. Pat. No. 5,323,510 and U.S. Pat. No. 5,584,095. In both of these documents, the vacuum cleaners have a base which includes a motor housing and a pair of wheels, and the connection between the base and the main body incorporates a universal joint which permits rotational movement of the main body with respect to the base about an axis which is oriented perpendicular to the rotational axis of the wheels and inclined with respect to the horizontal.
A further, less common, type of vacuum cleaner is a ‘stick vac’, which is so-called because it has a very slender stick-like main body. An example is shown in EP 1,136,029. Often, there is only a cleaner head at the base of the machine, with all other components of the machine being incorporated in the main body. While stick vacs are lighter weight and can be easier to manoeuvre than traditional upright cleaners, they generally have a small dust separator, a lower power motor and smaller filters, if any filters at all, and thus their improved maneuverability comes with the drawback of a lower specification.